Systems and methods for locking a sliding sleeve valve in an open position and/or a closed position to prevent inadvertent operation of the sleeve valve during other operations. A sliding sleeve valve locking assembly includes an outer housing defining a locking bore portion with a first locking groove formed therein, a sliding sleeve collet member having a collet finger with a tab shaped and sized to reside within the first locking groove. The sliding sleeve valve locking assembly also includes a collet locking member that is moveably disposed within the sliding sleeve collet member to selectively lock the sliding sleeve collet member within the locking bore portion.